Psychedelic drugs push the brain to a state never seen before

Measuring neuron activity has revealed that psychedelic drugs really do alter the state of the brain, creating a different kind of consciousness.

“We see an increase in the diversity of signals from the brain,” says Anil Seth, at the University of Sussex, UK. “The brain is more complex in its activity.”

Seth and his team discovered this by re-analysing data previously collected by researchers at Imperial College London. Robin Carhart-Harris and his colleagues had monitored brain activity in 19 volunteers who had taken ketamine, 15 who had had LSD, and 14 who were under the influence of psilocybin, a hallucinogenic compound in magic mushrooms. Carhart-Harris’s team used sets of sensors attached to the skull to measure the magnetic fields produced by these volunteers’ neurons, and compared these to when each person took a placebo.

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“We took the activity data, cleaned it up then chopped it into 2-second chunks,” says Seth, whose team worked with Carhart-Harris on the re-analysis. “For each chunk, we could calculate a measure of diversity.”

Higher state

Previous work had shown that people in a state of wakefulness have more diverse patterns of brain activity than people who are asleep. Seth’s team has found that people who have taken psychedelic drugs show even more diversity – the highest level ever measured.

These patterns of very high diversity coincided with the volunteers reporting “ego-dissolution” – a feeling that the boundaries between oneself and the world have been blurred. The degree of diversity was also linked to more vivid experiences.

There’s mounting evidence that psychedelic drugs may help people with depression in ways that other treatments can’t. Some benefits have already been seen with LSD, ketamine, psilocybin, and ayahuasca, a potion used in South America during religious rites.

“I think there’s an awful lot of potential here,” says Seth. “If you suddenly see things in a different way, it could give your outlook a jolt that existing antidepressants can’t because they work on the routine, wakeful state.”